Apparently We Can Fertilize Plants With Smoke Stacks at Coal Processors

Of the many nutrients plants need, some get more attention than others.

Nitrogen, for example, is of primary concern to farmers and gardeners. But there are other minerals that plants, some more than others, also need. According to new research from Ohio State University, those less-emphasized minerals could come from the smokestacks of coal plants.

The material we’re talking about here is gypsum, a sort of soft salt crystal, which has no end of uses: it can be turned into cement, plaster of Paris, drywall, used as a coagulant for making tofu, or as fertilizer. Gypsum contains high levels of calcium and sulfur, two of those nutrients that plants need, and can also help prevent both erosion of soil and the runoff of other, potentially toxic, fertilizers, like phosphorous. It’s one of the oldest and most commonly used non-nitrogen-based fertilizers in the world.

But where to get it? Gypsum is found naturally all over the world; China, the United States, and Iran all have massive deposits of gypsum and mines to extract it. This research from Ohio State, though, suggests a different source.

Fossil fuel power plants use a method called flue-gas desulfurization (FGD) to remove sulfur dioxide, a major pollutant and health risk, from the gases they emit from smokestacks. That method can produce what’s commonly known as FGD gypsum: basically, synthetic gypsum, almost identical to the stuff that’s dug up in mines.

The new research from Ohio State studied the ways FGD gypsum can be used in agriculture, and found that it could be very valuable. “The gypsum that is recovered has good quality,” says Warren Dick, the lead author of the study, in the study’s press release. “The gypsum particles are small and uniform in size making them quite reactive. This can be a real benefit in agriculture. We also determined that it is safe for agricultural use through many studies. Reusing it for agricultural purposes, instead of putting it in landfills, provides multiple wins.”

Reusing this FGD gypsum for agriculture is great news: it means there will be less need for gypsum mining, and allows the use of what normally would simply be a waste product for good. Who knew there was something valuable coming out of those smokestacks?